Method for manufacturing microelectromechanical combdrive device

• US 6,925,710 B1
• Filed: 03/27/2002
• Issued: 08/09/2005
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Scalf, Jennifer, Pannu, Satinderpal
• Primary Examiner(s): TRINH, MINH N
• Application Number:
  US10/112,063
• Time in Patent Office: 1,231 Days
• Field of Search: 298/47, 298/30, 298/46, 298/51, 295/95, 295/93, 296/031.3, 310/309, 359/254, 250/306, 250/442.11, 369/126, 361/283.3, 735/140.1, 735/143.2, 438/459
• US Class Current: 29/847
• CPC Class Codes: B81B 2201/033 Comb drives
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0136 Comb structures
• CPC Class Codes: B81C 1/00126 Static structures not provided for in groups B81C1/00031 - B81C1/00119
• CPC Class Codes: B81C 2203/051 Active alignment, e.g. using internal or external actuators, magnets, sensors, marks or marks detectors
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base
• CPC Class Codes: Y10T 29/49156 with selective destruction of conductive paths

Abstract

Methods of making microelectromechanical combdrive devices are disclosed. The device may optionally be formed using three device layers. A moveable element and flexure may be formed from a first device layer. The second device layer may be attached to the first and a first set of comb teeth are formed from the second device layer. One or more comb teeth in the first set extend from a major surface of the moveable element. A third device layer is attached to the second device layer and a second set of comb teeth are formed from the third device layer. An alignment target is formed in the first device layer. Corresponding alignment holes are formed in the second or third device layers.

Claims

1. A method for making a microelectromechanical combdrive device, comprising:

forming a moveable element from a first device layer;

attaching a second device layer to the first device layer

forming a first set of comb teeth from the second device layer, wherein one or more comb teeth in the first set extend from a major surface of the moveable element;

attaching a third device layer to the second device layer; and

forming a second set of comb teeth from the third device layer,

wherein the first set of comb teeth are aligned to the moveable element by;

before attaching the second device layer to the first device layer, forming an alignment target in the first device layer, and

after attaching the second device layer to the first device layer and before forming the first set of comb teeth, forming an alignment hole in the second device layer, wherein the alignment hole is roughly aligned to the alignment target.

2. The method of claim 1 wherein one or more comb teeth in the second set are configured to interdigitate with one or more comb teeth in the first set.

3. The method of claim 1 wherein the first device layer is part of a wafer that includes a handle substrate.

4. The method of claim 3, further comprising removing the handle substrate after attaching the third device layer to the second device layer.

5. The method of claim 3 wherein the handle substrate and first device layer are part of a silicon-on-insulator wafer.

6. The method of claim 5 wherein the silicon on insulator wafer includes an insulating layer disposed between the first device layer and the handle substrate.

7. The method of claim 5 wherein the silicon on insulator wafer includes an insulating layer disposed between the first device layer and the handle substrate.

8. The method of claim 1 wherein the moveable element includes a light deflecting portion.

9. The method of claim 8 wherein the light deflecting portion includes a mirror.

10. A method for making a microelectromechanical combdrive device, comprising:

forming a moveable element from a first device layer;

attaching a second device layer to the first device layer

forming a first set of comb teeth from the second device layer, wherein one or more comb teeth in the first set extend from a major surface of the moveable element;

attaching a third device layer to the second device layer; and

forming a second set of comb teeth from the third device layer,

wherein the second set of comb teeth are aligned to the first set of comb teeth by;

before attaching the third device layer to the second device layer, forming an alignment target in the second device layer, and

after attaching the third device layer to the second device layer and before forming the second set of comb teeth, forming an alignment hole in the third device layer, wherein the alignment hole is roughly aligned to the alignment target.

11. The method of claim 10 wherein one or more comb teeth in the second set are configured to interdigitate with one or more comb teeth in the first set.

12. The method of claim 10 wherein the first device layer is part of a wafer that includes a handle substrate.

13. The method of claim 12, further comprising removing the handle substrate after attaching the third device layer to the second device layer.

14. The method of claim 12 wherein the handle substrate and first device layer are part of a silicon-on-insulator wafer.

15. The method of claim 10 wherein the moveable element includes a light deflecting portion.

16. The method of claim 15 wherein the light deflecting portion includes a mirror.

17. A method for making a microelectromechanical combdrive device, comprising:

forming a moveable element and a flexure from a first device layer of a wafer having a first insulating layer disposed between the first device layer and a handle substrate;

forming an alignment target in the first device layer;

after forming the alignment target in the first device layer, attaching a second device layer to the first device layer such that the first device layer is disposed between the insulating layer and the second device layer;

forming a second insulating layer on a surface of the second device layer such that the second device layer is disposed between the oxide layer and the first device layer;

forming one or more comb teeth from the second device layer, wherein the one or more comb teeth extend from a major surface of the moveable element;

before attaching a third device layer to the second insulating layer, forming an alignment hole through the second insulating layer and the second device layer, wherein the alignment hole roughly aligns with the alignment target;

attaching the third device layer to the second insulating layer such that the second insulating layer is disposed between the second and third device layers;

forming one or more comb teeth from the third device layer, wherein the one or more comb teeth formed from the third device layer are configured to interdigitate with one or more of the comb teeth formed from the second device layer; and

releasing the movable element.

18. The method of claim 17, further comprising, before forming the comb teeth in the third device layer, removing the handle substrate and attaching a new handle substrate to the first insulating layer.

19. The method of claim 18 wherein the new handle substrate is attached to the first insulating layer with a photoresist.

20. The method of claim 18 wherein releasing the moveable element includes releasing the new handle substrate with a photoresist stripper.

21. The method of claim 17 wherein releasing the moveable element includes removal of selected portions of the first and second insulating layers.

22. A method for making a microelectromechanical combdrive device, comprising:

forming a moveable element and a flexure from a first device layer of a wafer having a first insulating layer disposed between the first device layer and a handle substrate;

attaching a second device layer to the first device layer such that the first device layer is disposed between the insulating layer and the second device layer;

forming a second insulating layer on a surface of the second device layer such that the second device layer is disposed between the oxide layer and the first device layer;

forming one or more comb teeth from the second device layer, wherein the one or more comb teeth extend from a major surface of the moveable element;

before attaching a third device layer to the second insulating layer, forming an alignment target in the second device layer;

attaching the third device layer to the second insulating layer such that the second insulating layer is disposed between the second and third device layers;

before forming one or more comb teeth from the third device layer, forming an alignment hole through the third insulating layer, wherein the alignment hole roughly aligns with the alignment target;

forming the one or more comb teeth from the third device layer, wherein the one or more comb teeth formed from the third device layer are configured to interdigitate with one or more of the comb teeth formed from the second device layer; and

releasing the movable element.

23. The method of claim 22, further comprising, before forming the comb teeth in the third device layer, removing the handle substrate and attaching a new handle substrate to the first insulating layer.

24. The method of claim 23 wherein the new handle substrate is attached to the first insulating layer with a photoresist.

25. The method of claim 23 wherein releasing the moveable element includes releasing the new handle substrate with a photoresist stripper.

26. The method of claim 22 wherein releasing the moveable element includes removal of selected portions of the first and second insulating layers.